The gov is just days away from enacting a sweeping reform of teacher-tenure laws, which currently guarantee lifelong jobs to even the worst educators.

And Christie has managed to twist the union into quite a pretzel: Its leaders now say they support making it easier to lay off the lemons among them.

“This legislation moves us in the right direction by making it harder to earn tenure, and less expensive and time-consuming to remove teachers who are not performing well,” said union boss Barbara Keshishian.

Yes, that’s the sound of Hell freezing over.

More precisely, it’s a labor leader explaining why she’s backing a bill that zaps the system that grants 98 percent of Newark’s new teachers near-automatic tenure — and jobs for life — every year without fail.

It’s a real testament to Christie’s skill. He called out the unions last year for running a system “where you have no rewards for excellence and no consequences for failure.”

And the Senate answered, passing a bill this week that requires four years of high ratings to win tenure, and lets schools revoke tenure and possibly fire teachers who get back-to-back negative reviews.

A watered-down version awaits passage in the Assembly, and a compromise bill should reach Christie’s desk soon.

This legislation is far from perfect: It fails to fix the “last in, first out” seniority rules that require the state to fire the newest teachers first whenever there are layoffs.

And, truth is, we’d rather see tenure abolished wholesale in Jersey and New York.

But the reform is a major achievement that should help dig public-school kids out of a failing school system.